1. Field of the Invention
The present invention relates to a thin-film magnetic head which locally projects an element part toward a recording medium by thermal expansion, so as to control the amount of floating.
2. Related Background Art
A thin-film magnetic head comprises a reproducing element which reads magnetic information from a recording medium by utilizing a magnetoresistive effect and a recording element, laminated on the reproducing element, for applying a recording magnetic field to the recording medium and thereby recording magnetic information thereon. As is well known, the reproducing element is formed between lower and upper shield layers by way of a gap layer, while the recording element in a perpendicular recording system, for example, is constituted by a main magnetic pole layer and a return yoke layer which are exposed at a surface opposing a recording medium while holding a magnetic gap layer therebetween, a recording coil which supplies a recording magnetic field to the main magnetic pole layer, and the like. Recently proposed are those in which a heater generating heat upon energization is provided near the reproducing and recording element s, so as to project an element part toward the recording medium by thermal expansion and locally narrow the gap between the recording medium and the reproducing and recording elements, thereby improving reproducing and recording performances. In such a conventional thin-film magnetic head, the amount of floating of the recording and reproducing elements from the recording medium greatly affects reading and writing capabilities, whereby it has been becoming important to control the amount of projection of the recording and reproducing parts. It has been proposed to hold a material having a small coefficient of thermal expansion within an element part of the thin-film magnetic head in order to control the amount of projection of the element part (Japanese Patent Application Laid-Open No. 2004-334995).